<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<style>
@layer base, special;
@layer special {
  #case1 { background-image: url(./special.bmp); }
}
@layer base {
  #case1 { background-image: url(./base.bmp); }
}
</style>
</head>
<body>
<blockquote id="case1">case1</blockquote>
</body>
</html>
